One atom of an element weighs $$3.32 \times {10^{ - 23}}g.$$    How many number of gram atoms are there in $$20\,kg$$  of the element ?

Solution :
$$\eqalign{ & {\text{Atomic mass of an element}} \cr & = {\text{Mass of one atom}} \times {N_A} \cr & = 3.32 \times {10^{ - 23}} \times 6.023 \times {10^{23}} \cr & = 19.99 \approx 20\,g \cr & {\text{No}}{\text{. of gram atoms}} \cr & = \frac{{{\text{Mass of element in gram}}}}{{{\text{Atomic mass in gram}}}} \cr & = \frac{{20 \times 1000}}{{20}} \cr & = 1000 \cr} $$